Someone comes to you with a problem - they feel as though their limbs do not belong to them. How can you possibly deal with such a huge and psychologically complex difficulty? It's going to be tough, but for now - squirt water in their ear. This actually stimulates a part of the brain that can take away the sensation of phantom limbs. Or occasionally, make them appear.

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Phantom limb pain or phantom limb sensation is a common feeling among those who have had their limbs amputated. It's fairly well known, but lesser known are syndromes in which people feel that their limbs are not their own. These can include dissociation with only one limb, as in "alien hand" syndrome. People feel as though one specific body part is not their own. The sense can become so strong that people will beg doctors to remove their limbs, and sometimes deny that the limb is part of them at all. Patients have told doctors that the arm attached to them has to belong to the last patient that the doctor saw, and was still in the room when the patient came in. For some patients that sense of alienation can extend to one entire side of their body. In still others, the feeling isn't localized. They feel a constant need to amputate what they see as extra or unwelcome body parts that have somehow become attached to them.

What can help these people? In the long term, doctors recommend both drugs and therapy to help them deal with their disorders. In the short term just squirt some water in their ear. Vestibular caloric stimulation - otherwise known as squirting hot or cold water into someone's ear - is used for a surprising amount of things, from distracting people during visual tests to checking the mental status of coma patients. It's a startling sensation, and it's not surprising that it would shake someone out of a mental test, or even disturb a light coma. It's been used to treat - temporarily - people with chronic pain. It sounds like the water would just distract those who have this particular sense of bodily estrangement from the sensation.

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But it's a little more complicated than that. Vestibular caloric stimulation will vary in effectiveness depending on the temperature of the water. The elimination of pain or of the sensation of an alien limb will depend on which ear the water is squirted into. And sometimes, instead of distracting people from sensations, the procedure will bring them up. A test was done in which doctors used the stimulation on patients who had had a limb amputated. Some of those patients had been experiencing phantom pain and sensation. Others had not. The procedure did help the dim the pain and the sensation in patients who experienced phantom limbs. In patients who hadn't, it suddenly brought on a temporary sensation of the limb they'd lost.

Why is a little water in the ear able to do all of this? Doctors think that it has something to do with the stimulation of the insular cortex of the brain. The insular cortex is tucked away inside the brain. It has been shown to have a lot to do with pain and pain management. It's also involved in speech and social perceptions. Some studies have found that it seems to be involved in empathetic pain. Images of the brain activity of people watching films of others suffering show engagement of this area of the brain when people have an empathetic response. This part of the brain might be the best way to tell people that they should feel something, whether it's a limb that doesn't exist anymore, or a feeling of being in sync with an otherwise estranged body part. This might also help people quiet otherwise unmanageable pain. It just happens to be stimulated through the ear.